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<html>
<head> 
<meta charset="utf-8"> 
<title>菜鸟教程(runoob.com)</title> 
</head>
<body>

<p id="demo"></p>
<script>
var r=Math.random();
var x=document.getElementById("demo")
if (r>0.5){
	x.innerHTML="<a href='http://www.runoob.com'>访问菜鸟教程</a>";
}
else{
	x.innerHTML="<a href='http://wwf.org'>Visit WWF</a>";
}
</script>

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